Biomechanics exam 1 - rutland

Which of the following would be harder to change direction? a) 5 kg moving at -5 m/sec b) 10 kg mass moving at 2 m/sec c) 2 kg mass moving at 12m/s

5 kg mass moving at -5 m/sec

Which of the following will lead to the greatest increase in angular momentum?

Increase torque; Increase the time the torque is applied

What is a resistance to change in velocity?

Inertia

Which of the following is an example of relative velocity?

The velocity of your car relative to another car

which of the following is a measure of inertia for a linear motion when a body is no moving?

mass

Which of the following is a measure of inertia for angular motion when a body is not rotating?

moment of inertia

Which of the following is a measure of inertia for linear motion when a body is moving?

momentum

If body A has a greater velocity than body B, then what is the velocity of body A relative to body B?

negative

What do two perpendicular axes represent?

plane

which of the following is an example of accommodating resistance

pneumatic devices

What is a body's location in a frame of reference?

position

A body's initial velocity was -20 m/sec and its final velocity was -10 m/seC) What was the average acceleration during this time?

positive

Which type of force will increase the velocity of a system

propulsive

What is a ratio between a change in one quantity and a change in time?

rate

What is represented by the slope of the force-time curve?

rate of force development

What quantity is derived from dividing one number by another number?

ratio

What is the correction factor for the opposite side of a right triangle?

sin theta

What quantity describes how fast something is moving without consideration for direction?

speed

Which of the following determines the acceleration of the center of mass?

the effective force

What variable describes how fast something is moving in a particular direction?

velocity

Which of the following quantities is a vector?

velocity

What is the correct symbol for angular velocity?

w

What is the force due to gravity?

weight

What is a push or pull by one body on another?

force

A dancer is preparing to jump. Assuming the same velocity, which take-off angle will give her the longest flight time?

greater than 45

If the landing elevation is higher than the take-off elevation, which take-off angle will give the farthest range?

greater than 45

What is represented by the area under the force-time curve?

impulse

What mechanical quantity is the product of force and change in time?

impulse

Which of the following will lead to greatest increase in angular momentum

increase angular velocity, increase MOI

which of the following will lead to the greatest increase in velocity a) Decrease the change in time; decrease the acceleration b) Decrease the change in time; increase the acceleration c) Increase the change in time; decrease the acceleration d) Increase the change in time; increase the acceleration

increase change in time, increase acceleration

Which of the following will lead to the greatest acceleration?

increase f, decrease m

Which of the following lead to the greatest increase in the moment of inertia?

increase mass, increase distance from axis of rotation

Which of the following will lead to the greatest increase in angular displacement? a) Increase the change in time; increase the angular acceleration b)Increase the change in time; decrease the angular velocity c) Decrease the change in time; increase the angular velocity

increase the change in time; increase the angular acceleration

What happens to the displacement if the velocity is increased for the same amount of time?

increases

What happens to the time to complete a movement if angular velocity is increased?

it decreases

What happens to the velocity if the acceleration is in the same direction as the direction of travel?

it increases

If a body is rotating with an w of -20 rads/sec and then changes to an w of -40 rads/sec, what can be said about the angular acceleration during this time?

it was positive

A body's initial position was +10 m from the origin and its final position was -10 m 1 second later. What was the body's displacement?

-20 min

what is the distance from the axis of rotation to the point of force application?

lever arm

Which of the following will lead to the greatest increase in linear momentum?

Decrease force; Decrease the time the force is applied

Which of the following will decrease the utilized coefficient of friction?

Decrease xFGRF ; Increase yFGRF

Which of the following will lead to the greatest increase in linear momentum?

Doubling the mass and doubling the linear velocity would have the same effect

what is the symbol for angular momentum

H

What is the correct symbol for moment of inertia?

I

Which of the following had the greatest displacement? a) Initial Position = -20 m; Mid Position = 0 m; Final Position = -20 m d) Initial Position = 0 m; Mid Position = +10 m; Final Position = +20 m c) Initial Position = +20 m; Mid Position = 0 m; Final Position = -20 m

Initial Position = +20 m; Mid Position = 0 m; Final Position = -20 m

You pause at the bottom of a bodyweight squat. What is the magnitude of the vertical FGRF during the pause?

bodyweight

Which of the following will lead to the greatest increase in angular velocity? a) Increase the change in time; increase the angular acceleration b) Increase the change in time; decrease the angular acceleration c) Decrease the change in time; increase the angular acceleration d) Decrease the change in time; decrease the angular acceleration

a

Which of the following has the greatest velocity in the x- direction?

a) magnitude of 10 with 0 degree angle

Angela has to sprint 30m to get to the ball. Which kinematic variable is most important to her success?

acceleration

What is represented by the slope of a velocity-time curve?

acceleration

What is represented by the slope of an angular velocity-time curve?

angular acceleration

What variable describes how quickly something is speeding up or slowing down its rotation?

angular acceleration

What is represented by the area under an angular velocity-time curve?

angular displacement

change in angular position

angular displacement

What is represented by the area under the torque-time curve?

angular impulse

Which of the following is a measure of inertia for angular motion when a body is rotating?

angular momentum

What is represented by the slope of an angular position-time curve?

angular velocity

Which of the following will lead to the greatest increase in the acceleration in the x- direction? a) Decrease magnitude of a; Decrease angle of a from the x- axis b) Decrease magnitude of a; Increase angle of a from the x- axis c) Increase magnitude of a; Decrease angle of a from the x- axis d) Increase magnitude of a; Increases angle of a from the x- axis

c

What is represented by the area under an angular velocity-time curve?

change in angular position

Which of the following will lead to the greatest increase in displacement? a) Decrease the change in time; decrease the velocity b) Decrease the change in time; increase the velocity c) Increase the change in time; decrease the velocity d) Increase the change in time; increase the velocity

d

What happens to the angular velocity if the angular acceleration is in the opposite direction of the direction of travel?

decreases

symbol for displacement

delta p

What is represented by the area under a velocity-time curve?

displacement

What is the physical length that a body has traveled during a period of time?

distance

A negative angular velocity means that the rotation is slowing down.

false

A negative velocity means that the body is slowing down.

false

A soccer player kicks a ball into the air. While the ball is in the air, the velocity in the x- direction is dependent on the velocity in the y- direction.

false

True or False? A braking force is always negative and leads to a decrease in velocity.

false

True or False? A larger wheel will be easier to rotate because it has a larger moment of inertia.

false

True or False? A steeper slope on an angular acceleration-time curve represents a higher velocity.

false

True or False? Acceleration is the most important variable in determining the outcome of a marathon.

false

True or False? In the vertical direction, the ground reaction force is the effective force.

false

True or False? The acceleration is negative if you are slowing down in the negative direction.

false

True or False? The acceleration is positive if you are speeding up in the negative direction.

false

True or False? The angular acceleration is positive if you are speeding up in the negative direction.

false

True or False? The effective force will always be in the body is moving.

false

True or False? The mass of a body has a bigger effect on the moment of inertia than the location of the center of mass of that body.

false

True or False? Velocity is a scalar.

false

Vectors can be added together using the rules of algebra.

false

Which of the following is equivalent to the frictional force during gait?

the ground reaction force in the x- direction

What is the correct symbol for angular position?

theta

True or False? A change in velocity causes an acceleration.

true

True or False? A steeper slope on a position-time curve represents a higher velocity.

true

True or False? All other things being equal, it would be easier to lift and drag an object across the floor than it would be to push it across the floor.

true

True or False? Assuming the same velocity of take-off, with the exception of a take-off angle of 45°, there are two take-off angles that will give an identical range.

true

True or False? Both radians per second and degrees per second are measures of angular velocity.

true

True or False? Displacement is a vector.

true

True or False? For a multi-body system, the location of the center of mass is not fixed.

true

True or False? Force is equal to the change in linear momentum over the change in time.

true

True or False? If a body starts with zero velocity and ends with zero velocity, then the area under the positive acceleration curve must be equal to the area under the negative acceleration curve.

true

True or False? In terms of movement, a force that pushes or pulls in the same direction will have the same effect.

true

True or False? In the horizontal direction, the ground reaction force is the effective force.

true

True or False? The cutting maneuver requires a decrease in momentum in the original direction of travel and an increase in momentum in the new direction of travel.

true

True or False? The negative sign in momentum indicates direction.

true

True or False? The sign of momentum is always in the direction of travel.

true

True or False? The sign of the angular velocity vector is always in the direction of the rotation.

true

True or False? The sign of the velocity vector is always in the direction of the displacement vector.

true

True or False? The velocity of a runner as he crosses the finish line is an example of instantaneous velocity.

true

True or False? Whenever there is a change in direction, the velocity will be zero at the instant the direction changes.

true

true or false? if a body starts with a zero velocity and ends with zero velocity, then the total change in momentum is zero

true